MEASUREMENT OF LARGE INFINITE DILUTION ACTIVITY-COEFFICIENTS OF NONELECTROLYTES IN WATER BY INERT-GAS STRIPPING AND GAS-CHROMATOGRAPHY

An inert gas stripping gas chromatography method was described for the determination of infinite dilution activity coefficients (gamma2infin ity) of organic compounds in water. The infinite dilution activity coe fficients for 31 compounds including many halogenated and aromatic com pounds were measured. In general, the gamma2infinity values measured b y gas stripping are in very good agreement with gamma2infinity values estimated from the inverse solubilities and other experimental measure ments. This suggests that when there is no directly measured data avai lable, gamma2infinity values estimated from the inverse of solubility can be used for the development and test of the models predicting limi ting activity coefficients. A major advantage of this method relative to headspace gas chromatography that improves its precision and accura cy is the fact that the absolute detector response is unimportant. The detector only needs to be linear.